1. Field of the Invention
The invention is directed generally to a method and apparatus that provides coherent phase noise in transceivers and, more particularly, to providing coherent phase noise in transceivers residing on multiple semiconductor chips by having multiple transceivers share a clock signal.
2. Related Art
To increase bandwidth in a wireless system, multiple transceivers have been used. In particular, use of a multiple input multiple output (MIMO) transceiver system that can transmit and receive simultaneously is one way to significantly increase the bandwidth efficiency of a wireless channel. Such MIMO systems increase the bandwidth and allow for a greater amount of data to be transmitted and received per unit time.
However, it has been found that MIMO systems may have reduced performance because a clock signal, such as a local oscillator signal, in each of the transceivers of the MIMO systems may have a different phase noise and, accordingly, the phase noise of the system is non-coherent. Non-coherent phase noise may adversely impact the MIMO system performance by decreasing bandwidth efficiency.
This application describes a method and apparatus that allows an internal local oscillator in each of the transceiver chips of a multi-chip MIMO system to be configured in either master or slave modes, thus allowing the local oscillator signal generated within the master chip to be distributed among all the slave chips so as to achieve a coherent local oscillator signal among all transceivers within the system.